This application claims the priority of Korean Patent Application No. 2002-8753 filed on Feb. 19, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to an apparatus and method for converting a frame rate, and more particularly, to an apparatus and method for converting a frame rate using operational vectors.
2. Description of the Related Art
A frame is a unit of a video image that consists of pixels, and thus, resolution of a video image depends on the number of pixels of a frame. For instance, a frame having a maximum resolution of 1920×1080 consists of 1920 pixels in the horizontal direction and 1080 pixels in the vertical direction. A frame rate refers to the number of frames that are transmitted per second. In order to transmit a video signal such as a television signal, an appropriate number of frames are transmitted in the units of seconds, based on visual characteristics of a human being.
In general, a video signal output from a video outputting apparatus is converted into a signal having a frequency that is permitted by a region to which the video signal is to be transmitted. For instance, the frequency of a video signal which is to be transmitted to Europe and China is converted into a vertical frequency of 50 Hz, and the frequency of a video signal which is to be transmitted to South Korea and North America is converted into a vertical frequency of 60 Hz. Therefore, frequency conversion is needed in order to enable one video outputting apparatus to output video signals of different frequencies. The frequency conversion is called frame rate conversion. In particular, the number of frames must be increased to convert a low frequency signal into a high frequency signal. In general, according to the frame rate conversion, the number of frames is increased by overlapping adjacent frames or by generating new frames using a detected motion vector based on a difference between adjacent frames.
Also, a more natural image is depicted by compensating a motion vector in a system requiring high resolution, so that the motion of a current image is changed according to the motion of the entire image. A motion vector is compensated by extracting a block of a predetermined size, which has a plurality of motion vectors including the motion vector which is to be compensated, and correcting a motion vector, which moves in a different direction from adjacent motion vectors, to move in the same direction as the adjacent motion vectors.
However, such a method of compensating a motion vector generates a compensation value based on the statistical distribution of adjacent motion vectors, and thus, there is a probability that the motion vector may be mistakenly compensated if the adjacent motion vectors contain errors. Further, if an actual image contains a portion that moves in the different direction from other portions, compensation for the portion may be performed without reflecting a change in the actual image even if a motion vector for the portion is detected.